In many areas of commerce, particularly the scientific, medical, and pharmaceutical areas, a need exists for cabinets offering economical storage and countertop space that can be adapted to a variety of uses and configurations, and that also can be readapted to other configurations at low cost and with minimal mechanical expertise as project demands and space requirements change over time. Although various types of modular storage cabinets and countertops have been manufactured to meet this need, such units are frequently substantially impossible or impractical to adapt to new configurations without considerable expense or the employment of skilled workmen to effect such changes.